The long-range objective of this project is to understand the mechanism used by bacterial cells to place the division site at its proper location within the cell. To approach this goal, the bacterial minicell locus (minB) will be studied since mutation of this locus results in aberrant placement of the division septum. The studies are based on recent work showing that the miniB locus codes for several genes that affect the division process. The studies will use a combination of genetics, biochemistry and immunoelectronmicroscopy to localize the minB gene products within the cell, to identify their interactions with each other and with other protein components of the cell division machinery, to probe for possible enzymatic functions of one of the proteins, and to examine the interaction of the minB system with another gene product (dicB) whose effect on the cell division process is likely to be mediated by the minB system.